Standard Quantum Physics states that the outcome of measurements for some distant entangled subsystems is instantaneously statistically correlated, whatever their mutual distance. This correlation presents itself as if there were a correlation at a distance with infinite speed. It is expressed by the Bell Theorem and has been experimentally verified over distances up to 1200 km (Yin et al. [14]) with

Thermospheric mass density (TMD) measurements are invaluable to accurately estimate and predict the position and velocity of orbiting objects in Low Earth Orbit (LEO). Existing observational methods and predictive models have some problems (e.g., accuracy, resolution, coverage, cost, etc.) to describe and forecast the actual air drag variations as required for practical applications. With the increasing

In this paper we use a collection of Gaussian striations to generate random realizations of a disturbed ionosphere. The formalism is developed here to create a two‐dimensional realization of electron density by summing a large number of Gaussian striations, uniformly distributed in space and with a given probability density function of their radii. We analytically calculate the power spectral density

In this paper, we discuss the mechanism for generating the lepton/baryon number and its subsequent conservation based on extra-dimensional evolution. The internal angular momentum of extra space is related to the lepton/baryon charge. Extra space metric is assumed to be initially asymmetric. Symmetries appear during inflation due to an increase in entropy. Using the multidimensional field toy model

In this work, we have constructed deceleration–acceleration and future evolution of cosmic expansion with curved dynamical dark energy models. Closed and open spatial curvatures are calculated by assuming that dark energy density does not exceed 85% of the closure density and by obtaining lower bounds on the ratio of dark energy to matter density, in terms of equation of state of dark energy. The range

The concept of boundary plays an important role in several branches of general relativity, e.g. the variational principle for the Einstein equations, the event horizon and the apparent horizon of black holes, the formation of trapped surfaces. On the other hand, in a branch of mathematics known as geometric measure theory, the usefulness has been discovered long ago of yet another concept, i.e. the

We review (and extend) the analysis of general theories of all interactions (gravity included) where the mass scales are due to dimensional transmutation. Quantum consistency requires the presence of terms in the action with four derivatives of the metric. It is shown, nevertheless, how unitary is achieved and the classical Ostrogradsky instabilities can be avoided. The four-derivative terms also allow

Using the light-front holographic model, we study the transverse momentum-dependent parton distributions (TMDs) for the case of pion. At leading twist, the unpolarized parton distribution function f1π(x,k⊥2) and the Boer–Mulders function h1π⊥(x,k⊥2) are obtained for pion. We calculate both the functions using the light-front holographic model with spin improved wave function and compare the predicted

We study a generalized KG-oscillator in the five-dimensional cosmic string geometry background with a magnetic field and quantum flux using Kaluza–Klein theory under the effects of a Cornell-type scalar potential, and observe the gravitational analogue of the Aharonov–Bohm effect. We see that the scalar potential allows the formation of bound states solution, and the energy eigenvalue depends on the

We propose the description of superintegrable models with dynamical so(1.2) symmetry, and of the generic superintegrable deformations of oscillator and Coulomb systems in terms of higher-dimensional Klein model (the noncompact analog of complex projective space) playing the role of phase space. We present the expressions of the constants of motion of these systems via Killing potentials defining the

We study d-dimensional black holes surrounded by dark energy (DE), embedded in D-dimensional M-theory/superstring inspired models having AdSd×𝕊d+k space–time where D=2d+k. We focus first on the thermodynamical Hawking–Page phase transitions, whose microscopical origin is linked to N coincident (d−2)-branes supposed to live in such inspired models. Interpreting the cosmological constant as the number

The Snyder–de Sitter model is an extension of the Snyder model to a de Sitter background. It is called triply special relativity (TSR) because it is based on three fundamental parameters: speed of light, Planck mass and cosmological constant. In this paper, we study the three-dimensional DKP oscillator for spin-0 and spin-1 in the framework of Snyder–de Sitter algebra in momentum space. By using the

We study the problem of the instability of inhomogeneous radiation universes in quadratic Lagrangian theories of gravity written as a system of evolution equations with constraints. We construct formal series expansions and show that the resulting solutions have a smaller number of arbitrary functions than that required in a general solution. These results continue to hold for more general polynomial

We analyze the Abraham–Minkowski problem known from classical electrodynamics from two different perspectives. First, we follow a formal approach, implying use of manifolds with curved space sections in accordance with Fermat’s principle, emphasizing that the resulting covariant and contravariant components of the photon four-momentum are a property linked to the Minkowski theory only. There is thus

It is shown that first-order Darboux transformations for the two-dimensional massless Dirac equation with scalar potential and for the Schrödinger equation are the same up to a change of coordinates. As a consequence, we obtain a closed-form representation of iterated, higher-order Darboux transformations for our Dirac equation. We use the formalism to generate several new exactly-solvable Dirac systems

The effect of the geometry (deviation from the flat space) on the quantum evolution of the momentum and position of a free particle is discussed. It is shown that beginning with a wave-packet of minimum uncertainty (a Gaussian wave), there is a usual increase in the product of the volume uncertainties in the momentum and position space, as seen in the quantum mechanics on a flat spaces. But there is

We consider an elastic medium with the distortion of a circular curve into a vertical spiral. Then, we investigate the topological effects of a charged screw dislocation on the attractive inverse-square potential that stems from the interaction of the induced electric dipole moment of a neutral quasiparticle with an electric field. We show that an analogue of the Aharonov–Bohm effect for bound states

We analyze nonrelativistic quantum effects on a neutral particle due to the presence of an attractive inverse-square potential that stems from the effects of the Lorentz symmetry violation determined by the parity-even sector of the tensor (KF)μναβ. We show that bound states solutions to the Schrödinger equation can be achieved. We go further by considering a repulsive inverse-square potential yielded

Abstract The geomorphological and geological analysis of the surface of three primary and ten secondary landing ellipses (15 × 30 km) for the Russian Luna-Glob automated scientific station (Luna-25) is presented. The earlier selected landing ellipses are found in the sector of 65°–85° S and 0°–60° E of the lunar southern hemisphere. The geological characteristics of the ellipse include the analysis

Abstract— The results of numerical modeling of the vertical fall of ten-kilometer asteroids onto a solid surface and into an ocean with a depth of 1 to 7 km are presented. The calculations obtained the maximum masses of water and soil emitted into the atmosphere, as well as the masses of water and soil remaining in the atmosphere 30 minutes after the impact. It is concluded that that when asteroids

Abstract The restricted elliptic doubly averaged three-body problem is considered. The terms up to the second order inclusive with respect to the orbital eccentricity of the perturbing body are retained in the expansion of the perturbing function. The elements of the elliptical orbit for the perturbed body are deemed arbitrary. The special, so-called linked orbits of a negligible-mass body are investigated

Abstract— The discovery of the first interstellar comet 2I/Borisov confirmed the astronomers’ speculation that the passage through the solar system of relatively large objects (asteroids and comets) formed outside of it is a common occurrence. There may be many such objects, but their discovery is still a rare case. Large professional telescopes and existing observation programs with these telescopes

Abstract— Within the framework of Tsallis nonextensive statistics, the criteria for the Jeans gravitational instability are derived for a self-gravitating protoplanetary disk, whose substance consists of a mixture of a conducting ideal q-gas and modified radiation of a photon gas. The instability criteria are derived from the corresponding dispersion relations written for both neutral disk matter and

Abstract The paper considers the free molecular flow of gas through the dusty porous surface layer of a comet nucleus. The study is based on computer models of generation of a porous medium and Knudsen gas diffusion. We consider various types of homogeneous and heterogeneous layers constructed from nonintersecting spheres, including layers that contain microcracks or inner cavities. Using the test-particle

Abstract In the current investigation we have studied the distribution as well as the asymmetry of solar X-ray flares during the period 1976–2017 which corresponds to solar cycle 21, 22, 23 and the almost complete solar cycle 24. The study of the N–S distribution of soft X-ray flares during solar cycles 21, 22, 23 and 24 reveals that the 10°–20° latitude band produced maximum number of soft X-ray flares

Abstract We estimate the contribution of the molecular hydrogen dissociation processes, which are induced by the extreme UV radiation and the accompanying flux of photoelectrons, to the formation of a fraction of suprathermal atomic hydrogen in the Н2 → Н transition region and the corresponding escape flux from the extended upper atmosphere of an exoplanet—the hot Neptune GJ 436b (Gliese 436b). We

Results are presented of a comparison between solar-wind speed estimates made using the time delays between three pairs of 327 MHz antennas at the Institute for Space-Earth Environmental Research (ISEE) of Nagoya University and by modeling the temporal power spectra observed with the 111 MHz Big Scanning Array (BSA) antenna at the Lebedev Physical Institute (LPI). The observations were made for 6 years

We report on a multi-wavelength analysis of the 26 January 2014 solar eruption involving a coronal mass ejection (CME) and a Type-II radio burst, performed by combining data from various space and ground-based instruments. An increasing standoff distance with height shows the presence of a strong shock, which further manifests itself in the continuation of the metric Type-II burst into the decameter–hectometric

We use experimental data of the FIRST survey to construct the radiation pattern of external components of extended radio sources. The radiation pattern differs from spherical. The greatest deviation from sphere is observed in the region facing the central component, where there is a deep minimum. The minimum of radiation in the beam pattern is associated with the region where the regular magnetic field

We performed the comparative analysis of the properties of Ap and Am stars. It is shown that the main differences in the formation and evolution of these objects are due to the influence of a magnetic field in Ap stars.

The paper presents magnetic field measurements for 15 chemically peculiar (CP) stars of subgroup 1b in the Orion OB1 association. We have found that the proportion of stars with strong magnetic fields among these 15 CP stars is almost twice as large as in subgroup 1a. Along with this, the age of subgroup 1b is estimated as 2 Myr, and the age of subgroup 1a is in the order of 10 Myr. The average root-mean-square

Orbits of 20 visual double stars discovered by P. Couteau are computed for the first time. The observations for four of these stars, COU 384, COU 1067, COU 1681, and COU 2388, span arcs greater than or approximately equal to 180 degrees. Since the time of their discovery the stars, COU 384 and COU 2388 have already completed one revolution. COU 338, COU 567, COU 1003, COU 1607, and COU2086 have many

In this work, the orbital elements are improved and the total masses of the three close visual binary systems CVBSs: HIP 11352, HIP 70973, and HIP 72479 are precisely calculated. The calculations were performed based on an assessment of the latest Gaia DR2 and Hipparcos trigonometric parallax measurements. The morphology and kinematics of orbits are fitted to the observational data available in the

We estimated a number of parameters for small groups of stars in the open Pleiades star cluster using Gaia DR2 coordinate and proper motion data for stars in the region of radius d = 2.5° relative to the center of the cluster on the celestial sphere. We selected 36 wide pairs of stars with magnitudes mG < 15m and velocities of the stars in these pairs with respect to their geometric centers close to

We present the “StoP” photometer-polarimeter (Stokes-polarimeter) used for observations with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences since the beginning of 2020. We describe the instrument and its parameters in observations performed in the photometric and polarimetric modes. We demonstrate the capabilities of the instrument through the polarimetry

Ultraluminous X-ray sources (ULXs) were identified as a separate class of objects in 2000 based on data from the Chandra X-Ray Observatory. These are unique objects: their X-ray luminosities exceed the Eddington limit for a typical stellar-mass black hole. For a long time, the nature of ULXs remained unclear. However, the gradual accumulation of data, new results of X-ray and optical spectroscopy,

Deuterium represents the only bound isotope in the universe with atomic mass number A=2. Motivated by the possibility of other universes, where the strong force could be stronger, this paper considers the effects of bound diprotons and dineutrons on stars. We find that the existence of additional stable nuclei with A=2 has relatively modest effects on the universe. Previous work indicates that Big

Loosely captured orbits with circulating and pulsating eccentricity vectors have a variety of attractive mission design properties, including low insertion costs, near-circular and highly eccentric phases, mid- to high inclinations, long-term stability, and spatially distributed close approaches. Such orbits are the known result of averaging third-body perturbations over the spacecraft and system motions

Severe space weather was identified as a risk to the UK in 2010 as part of a wider review of natural hazards triggered by the societal disruption caused by the eruption of the Eyjafjallajökull volcano in April of that year. To support further risk assessment by government officials, and at their request, we developed a set of reasonable worst‐case scenarios and first published them as a technical report

In this study, we investigate the energy partition of four confined circular-ribbon flares (CRFs) that occurred close to solar disk center. The flares are observed simultaneously by the Solar Dynamics Observatory (SDO), the Geostationary Operational Environmental Satellites (GOES), and the Ramaty Hight Energy Solar Spectroscopic Imager (RHESSI). We calculate different energy components, including the

The editors thank the 2020 peer reviewers

The present study explores the center‐of‐mass (Hc) of the ionosphere as the effective ionospheric varying shell height (VSH). We presents global ionospheric maps GIM‐Hc produced with IRI‐Plas model by assimilating the instant GIM‐TEC maps provided by JPL from 1994 to present which allows obtaining global maps of the F2 layer critical frequency, GIM‐foF2 (or NmF2) and peak height, GIM‐hmF2. Ratio TEC/NmF2

No abstract is available for this article.

We present simultaneous magnetic field measurements for the limb solar flare of 1981 July 17 using of the Ca II K, Hδ, He I 4471.5 Å and Hβ lines. For two moments during the flare, which differ in time by 16 min, we analyzed Stokes I ± V profiles of these lines from observations made on the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of Taras Shevchenko National

A Meteor and ionospheric Irregularity Observation System (MIOS) - optical subsystem, which currently consists of 26 video cameras (4 spectrographs) at two stations Sanya (18.3°N, 109.6°E) and Ledong (18.4°N, 109°E) separated by about 70 km was developed. One of the major goals of MIOS is to study how the entry of meteoroids into the Earth’s atmosphere changes the ionosphere through combining measurements

The study of ratio α(=λÀÀ⊥/λ||) of galactic cosmic ray (GCR) free paths normal (λ⊥) and parallel (λ||) to the mean interplanetary magnetic field (IMF) B is continued with annual mean GCR solar diurnal anisotropy (SDA) data of the Cheltenham/Fredericksburg shielded ion chamber (CH-IC) for 1936-1977 previously analyzed by Bieber and Chen (1991) but not corrected for atmospheric temperature effect. This

Electrostatic dust transportation is one of the fundamental sources for dust activity on airless planetary bodies. Even though a series of laboratory experiments have been performed to improve our understanding of the physics behind the electrostatic dust mobilization, there are several factors to investigate such as the launch angles, the lofted particle sizes, the traveling distance of the lofted

Spatially explicit measurement of Above Ground Biomass (AGB) is crucial for the quantification of forest carbon stock and fluxes. To achieve this, an integration of Optical and Synthetic Aperture Radar (SAR) satellite datasets could provide an accurate estimation of forest biomass. This will also help in removing the uncertainties associated with the single sensor-based estimation approaches. Therefore

Hayabusa2 is the Japanese Asteroid Return Mission and targeted the carbonaceous asteroid Ryugu, conducted by the Japan Aerospace Exploration Agency (JAXA). The goal of this mission was to conduct proximity operations including remote sensing observations, material sampling, and a Small Carry-On Impact experiment, as well as sample analyses. As of September 2020, the spacecraft is on the way back to

The safe lander dynamics is an important part of the lunar landing mission. In this paper, a discrete element method (DEM) for lunar soil is set up, and the finite element method (FEM) for the lander is set up by shell elements and beam elements. The lander is regarded as a multibody system composed of a cabin, legs and footpads, and its motion characteristics are solved by multibody dynamics (MBD)

To investigate the envelope radiation characteristic of stratospheric airship, three kinds of airship models with different dimensions (fineness ratio of 3,4,5) are selected. After establishing the thermal equilibrium equations of the selected models, the influence of the envelope radiation characteristic on the envelope and airship gas is first addressed to determine the optimal fineness ratio by

We investigate some models of compact objects in the general relativity theory with cosmological constant Λ, based on two density profiles, one of them attributed to Stewart and the other one to Durgapal and Bannerji, proposed in the literature to model “neutron stars”. For them, a nonlocal equation of state with cosmological constant is obtained as a consequence of the chosen metric. In another direction

We will mainly discuss the measurable angle (local angle) of the light ray ψP at the position of the observer P instead of the total deflection angle (global angle) α in Kerr spacetime. We will investigate not only the effect of the gravito-magnetic field or frame dragging due to the spin of the central object but also the contribution of the motion of the observer with a coordinate radial velocity

We propose a codimension two warped braneworld model within the teleparallel f(T) gravity. Asymptotically, the bulk geometry converges to an AdS6 spacetime whose cosmological constant is produced by the torsion parameters. Furthermore, the torsion induces an AdS-dS transition on the exterior region. As the torsion parameters vary, the brane undergoes a phase transition from a thick string-like brane

In this paper, we investigate the entropy of the free gravitational field for a given epoch for some well-known isotropic and anisotropic cosmologies. We use the definition of gravitational entropy proposed by Clifton, Ellis and Tavakol, where the 2-index square root of the 4-index Bel–Robinson tensor is taken to be the energy– momentum tensor for the free gravity. We examine whether in the vicinity

This topical collection summarizes recent advances in observing and modeling irradiance variations of the Sun and Sun-like stars, emphasizing the links between surface magnetic fields and the resulting solar and stellar variability. In particular, the articles composing this collection summarize recent progress in i) solar-irradiance measurements; ii) modeling of solar- and stellar-irradiance variability;

Pierre Gassendi (1592 – 1655) carried out sunspot observations during the 1630s. This period is particularly interesting because it occurred a few years before the Maunder Minimum. Gassendi was the second most active sunspot observer in that decade, surpassed only by Christoph Scheiner. Moreover, the sunspot observations made by Gassendi are of interest because most of them were made in days when no

The 13 June 2010 event was chosen as an example to find spots on a CME-related shock where type II radio bursts were generated. We used the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) data to find the shock and calculate the emission measure distribution over the solar limb in order to obtain various plasma characteristics ahead of and behind the shock front. A region

The minimum of the previous solar cycle, Solar Cycle 24, occurred in December 2019, which also marked the start of the new Solar Cycle 25. The first radio bursts of the new solar cycle were observed in the spring season 2020. In this work we will present three type III solar bursts which were observed in May and June 2020 at radio frequencies between 18 – 90 MHz. There are two radio observatories in

The Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM) was installed on the ISS to measure high-energy cosmic-ray elemental spectra for the charge range Z=1 to 26. The ISS-CREAM instrument includes a tungsten scintillating-fiber calorimeter preceded by a carbon target for energy measurements. The carbon target induces hadronic interactions, and showers of secondary